1. Field of the Invention
The present invention is related to an injection quantity control apparatus provided to an internal combustion engine, and in particular to an injection quantity control apparatus provided to an internal combustion engine in which fuel is continuously injected.
2. Description of the Related Art
Conventionally, as disclosed in "My Maintenance Note," Naoyuki Yokoyama, Japan Aeronautical Engineers' Association, Jul. 10, 1981), there is known an injection quantity control apparatus provided to an internal combustion engine for an aircraft. This control device includes a first chamber and a second chamber.
The first chamber is divided into a static pressure chamber and a total pressure chamber by a first diaphragm. A static pressure and a total pressure generated in an intake pipe of the engine are introduced into the static pressure chamber and the total pressure chamber, respectively. Thus, a dynamic pressure is generated between the static pressure chamber and the total pressure chamber in accordance with a specific volume of intake air. Hereinafter, this dynamic pressure is referred to as a first differential pressure. A force is exerted on the first diaphragm in accordance with the first differential pressure.
The second chamber is divided into a back pressure chamber and a fuel chamber by a second diaphragm. A valve mechanism is provided in the fuel chamber. Fuel is delivered from the fuel chamber through the valve mechanism. Thus, an amount of fuel delivered from the fuel chamber is adjusted in accordance with an opening of the valve mechanism. The fuel chamber is supplied with fuel which is pumped up by a fuel pump through a mixture valve. An opening of the mixture valve can be changed by a mixture lever being manually operated by an operator. When fuel is delivered from the fuel chamber through the valve mechanism, a fuel pressure in the fuel chamber is decreased from a discharge pressure of the fuel pump by a value corresponding to a pressure drop across the mixture valve. On the other hand, the back pressure chamber is directly supplied with fuel discharged by the fuel pump. Thus, between the back pressure chamber and the fuel chamber, there is generated a differential pressure in accordance with the pressure drop across the mixture valve, that is, a differential pressure in accordance with a product of a flow resistance of the mixture valve and an amount of delivered fuel. Hereinafter, this differential pressure is referred to as a second differential pressure. A force in accordance with the second differential pressure is exerted on the second diaphragm.
A valve body of the above-mentioned valve mechanism is connected to the first and second diaphragms so that a first force generated by the first differential pressure is exerted thereon in a valve opening direction and a second force generated by the second differential pressure is exerted thereon in a valve closing direction. Thus, the valve mechanism is maintained to be in a state where the first and second forces are balanced. As mentioned above, the first differential pressure corresponds to a specific volume of intake air and the second differential pressure corresponds to an amount of fuel which is delivered from the fuel chamber. Thus, the injection quantity control apparatus can adjust an amount of fuel delivered therefrom in accordance with a specific volume of intake air. The fuel which is delivered from the injection quantity control apparatus is supplied to injection nozzles, and the nozzles continuously inject fuel into the respective intake pipes.
Additionally, the second differential pressure changes in accordance with an opening of the mixture valve, as mentioned above. Thus, it is possible to adjust an injection quantity by manually operating a mixture lever so that an opening of the mixture valve is changed.
While the aircraft is in flight, it is necessary to adjust the injection quantity so that a lean air-fuel ratio is achieved in view of improving fuel economy. However, according to the above-mentioned conventional injection quantity control apparatus, the operator must manually operate the mixture lever while monitoring, for example, an exhaust gas temperature. Such an operation forces a burden on a pilot of the aircraft.